Various processes have been proposed for slumping glass or shaping glass to impart a bend or curvature thereto. One process is a “dropout” process. Vacuum forming processes have also been used to shape glass softened by heating. However, numerous disadvantages and drawbacks are associated with the dropout and vacuum forming processes for slumping glass. These processes utilize fixed alignment systems to secure the edges of the glass to the molds. However, these fixed alignment systems can inhibit the glass from dropping or sagging into the cavities of the molds. This results in formation of protruding, perimetrical flanges in the glass after shaping, such flanges circumscribing or surrounding portions of the glass that have been allowed to drop or sag into the cavities. Depending on the intended use for the shaped glass, such flanges may be undesirable and require removal. Removal of the flanges adds additional cost, labor and time to the glass shaping processes.
Another drawback is that the glass tends to be undesirably stretched when they drop or sag into the molds. Additionally, although dropout processes are effective for relatively thick (e.g. ½ to 1 inch thick) glass, such processes are generally unsuitable for relatively thin (e.g. ¼ inch thick or less) glass. Most dropout processes involve heating the glass relatively rapidly, which is detrimental to relatively thin glass and/or “art” glass. Some dropout processes also involve multiple heating cycles (firings), movement of the glass during heating, repositioning of the glass in or on the molds and/or transfers of the glass between different molds, thusly adding undesirably to the complexity, cost, time and labor for the glass shaping processes.
Furthermore, these processes typically involve contacting the glass with chemicals, gases or extraneous mechanical components, which is undesirable. Additionally, when vacuum forming, the glass may crack or otherwise be impaired due to inconsistencies or lack of control in the applied vacuum. Moreover, the appearance of the glass may be undesirably altered due to application of the vacuum, which is a significant drawback when aesthetics are important. Furthermore, in each of these processes, after the glass is slumped, the glass must still be grinded to form the finished edges.